Wireless communications is becoming increasingly important, with wireless systems finding their way into every growing numbers of applications. Wireless systems have become ubiquitous in the military environment.
Wireless communications can involve transmitting and receiving a radio frequency signal (e.g., a propagating radio wave). As spectrum has become scarcer, systems have been moving to higher and higher frequency communications bands. Many communications systems operate at carrier frequencies of several giga-Hertz (GHz) and above.
Transmission and reception of radio frequency signals has traditionally required a large number of analog components. Moreover, the components typically used in the radio frequency electronics of a transmitter and receiver have not enjoyed the same rapid advances in miniaturization and cost reduction as have digital components. Hence, the radio frequency electronics portion of transmitters and receivers often consume a large portion of allowable size, weight, and power budgets for equipment designs.
One trend in wireless communications is the use of so-called software-defined radios. In general, a software-defined radio uses digital processing to perform functions traditionally performed in analog components. Unfortunately, since propagating radio waves and other types of wireless signals are in an analog form, it is still necessary to convert between the analog domain and the digital domain. Moreover, components available for performing such conversions have limited operating speeds. Accordingly, there are a number of challenges in attempting to implement software define radios, particularly at frequencies of 2 GHz and above.